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final harvest. A temperature x cultivar interaction was recorded for flower number,
pod number, pod yield and HI (Table 8.7).
Of the two cultivars, ICGS 11 was more tolerant to high temperature. In both
cultivars, a decrease in pod yield and HI was recorded under high-temperature treat-
ments, but the decrease was significantly less in ICGS 11 compared to the decrease
in TMV 2. Cultivar ICGS 11 maintained a high pod yield and high HI under high-
temperature treatments (T3 and T4). On the other hand, a severe decrease in pod
yield and HI were recorded in TMV 2. The higher pod yield and HI in ICGS 11
can be attributed to greater flower fruit-set (i.e. ratio of pod to flower number) and
pod number. In contrast, in TMV 2, reduction in flower number and fruit set was
recorded, and so pod number was decreased on exposure to high temperature.

8.4 Discussion

Studies to identify temperature × water stress interactions (Craufurd et al. 1999 ) or
to screen genotypes for heat tolerance have been conducted mainly in controlled
environments (Prasad et al. 1999a, 1999b, 2000 ; Wheeler et al. 1997 ). Under these
conditions, the temperature increase follows a square-wave pattern (Fig. 8.1).

8 Effect of High Temperature and Water Stress on Groundnuts ...

Water stress Cultivar

TMV 2 ICGS 11

Flower number

Irri 32 53

WS 34 44

SED 2.1*

Pod number

Irri 12 24

WS 11 17

SED 1.5*

Pod yield

Irri 91.9 148.5

WS 66.1 88.4

SED 6.4**

Harvest index

Irri 0.23 0.33

WS 0.21 0.28

SED 0.017*

IR irrigated, WS water stress, SLA specific leaf area.

*, ** indicate significance at 0.05 and 0.01 levels of probability,

respectively

Table 8.6 Interaction
between genotype and
water stress treatments
for flower number
(plant−1) at 30 DAA, pod
number (plant−1), pod
yield (g m−2) and harvest
index as observed at final
harvest